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1 /* mpi-add.c - MPI functions
2 * Copyright (C) 1998, 1999, 2000, 2001 Free Software Foundation, Inc.
3 * Copyright (C) 1994, 1996 Free Software Foundation, Inc.
5 * This file is part of GnuPG.
7 * GnuPG is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
12 * GnuPG is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
21 * Note: This code is heavily based on the GNU MP Library.
22 * Actually it's the same code with only minor changes in the
23 * way the data is stored; this is to support the abstraction
24 * of an optional secure memory allocation which may be used
25 * to avoid revealing of sensitive data due to paging etc.
26 * The GNU MP Library itself is published under the LGPL;
27 * however I decided to publish this code under the plain GPL.
30 #include "mpi-internal.h"
33 * Add the unsigned integer V to the mpi-integer U and store the
34 * result in W. U and V may be the same.
36 int mpi_add_ui(MPI w
, const MPI u
, unsigned long v
)
39 mpi_size_t usize
, wsize
;
46 /* If not space for W (and possible carry), increase space. */
48 if (w
->alloced
< wsize
)
49 if (mpi_resize(w
, wsize
) < 0)
52 /* These must be after realloc (U may be the same as W). */
56 if (!usize
) { /* simple */
59 } else if (!usign
) { /* mpi is not negative */
61 cy
= mpihelp_add_1(wp
, up
, usize
, v
);
64 } else { /* The signs are different. Need exact comparison to determine
65 * which operand to subtract from which. */
66 if (usize
== 1 && up
[0] < v
) {
70 mpihelp_sub_1(wp
, up
, usize
, v
);
71 /* Size can decrease with at most one limb. */
72 wsize
= usize
- (wp
[usize
- 1] == 0);
82 int mpi_add(MPI w
, MPI u
, MPI v
)
85 mpi_size_t usize
, vsize
, wsize
;
86 int usign
, vsign
, wsign
;
88 if (u
->nlimbs
< v
->nlimbs
) { /* Swap U and V. */
94 if (RESIZE_IF_NEEDED(w
, wsize
) < 0)
96 /* These must be after realloc (u or v may be the same as w). */
105 if (RESIZE_IF_NEEDED(w
, wsize
) < 0)
107 /* These must be after realloc (u or v may be the same as w). */
114 if (!vsize
) { /* simple */
115 MPN_COPY(wp
, up
, usize
);
118 } else if (usign
!= vsign
) { /* different sign */
119 /* This test is right since USIZE >= VSIZE */
120 if (usize
!= vsize
) {
121 mpihelp_sub(wp
, up
, usize
, vp
, vsize
);
123 MPN_NORMALIZE(wp
, wsize
);
125 } else if (mpihelp_cmp(up
, vp
, usize
) < 0) {
126 mpihelp_sub_n(wp
, vp
, up
, usize
);
128 MPN_NORMALIZE(wp
, wsize
);
132 mpihelp_sub_n(wp
, up
, vp
, usize
);
134 MPN_NORMALIZE(wp
, wsize
);
138 } else { /* U and V have same sign. Add them. */
139 mpi_limb_t cy
= mpihelp_add(wp
, up
, usize
, vp
, vsize
);
152 * Subtract the unsigned integer V from the mpi-integer U and store the
155 int mpi_sub_ui(MPI w
, MPI u
, unsigned long v
)
158 mpi_size_t usize
, wsize
;
165 /* If not space for W (and possible carry), increase space. */
167 if (w
->alloced
< wsize
)
168 if (mpi_resize(w
, wsize
) < 0)
171 /* These must be after realloc (U may be the same as W). */
175 if (!usize
) { /* simple */
179 } else if (usign
) { /* mpi and v are negative */
181 cy
= mpihelp_add_1(wp
, up
, usize
, v
);
184 } else { /* The signs are different. Need exact comparison to determine
185 * which operand to subtract from which. */
186 if (usize
== 1 && up
[0] < v
) {
191 mpihelp_sub_1(wp
, up
, usize
, v
);
192 /* Size can decrease with at most one limb. */
193 wsize
= usize
- (wp
[usize
- 1] == 0);
202 int mpi_sub(MPI w
, MPI u
, MPI v
)
208 if (mpi_copy(&vv
, v
) < 0)
210 vv
->sign
= !vv
->sign
;
211 rc
= mpi_add(w
, u
, vv
);
214 /* fixme: this is not thread-save (we temp. modify v) */
216 rc
= mpi_add(w
, u
, v
);
222 int mpi_addm(MPI w
, MPI u
, MPI v
, MPI m
)
224 if (mpi_add(w
, u
, v
) < 0 || mpi_fdiv_r(w
, w
, m
) < 0)
229 int mpi_subm(MPI w
, MPI u
, MPI v
, MPI m
)
231 if (mpi_sub(w
, u
, v
) < 0 || mpi_fdiv_r(w
, w
, m
) < 0)